Production of voluminous yarn



June 1959 R. A. A. wlLLENs ,890,568

PRODUQTION OF VOLUMINOUS YARN Filed June 4, 1957 I? F I6. I I

in I

United States Patent PRODUCTION or VOLUMINOUS YARN Robert AlfredArchibald Willens, London, England, assignor to British CelaneseLimited, a company incorporated of Great Britain Application June 4,1957; Serial No. 663,527

Claims priority, application Great Britain June 19, 1956 7 Claims. (Cl.57-157) immediately before it enters said zone, setting in the I fibersof the yarn the distortion imposed by the falsetwist, withdrawing theyarn from said zone and collecting it an a linear speed less than thatat which it was fed into said zone. In this way, it has been found thatthe natural tendency of the yarn to contract after being stretched canbe made use of to impose a moderate and controllable degree of tensionon the yarn while it possesses twist and while the distortions impartedby said twist are being set, whereby the setting is rendered moreeffective and more permanent. It is necessary that the relative speedsof withdrawal from the source of supply and feeding into thefalse-twisting zone should impose on the yarn a degree of stretch inexcess of its elastic limit, i.e. the degree at which the stretchimparted is wholly and immediately recoverable on releasing the strain.By exceeding this elastic limit, some degree of delayed recovery is ableto take place in the zone in which false-twisting and setting areeffected. However, as the elastic limit (in the sense defined above) ofnearly all textile yarns, even including wholly synthetic yarns, is verylow, a moderate degree of stretch of 3 to 4% or even less is suflicientto produce a desirable effect. It is preferred, however, to use a higherdegree of stretch of the order of 5 to 7 /2%, or even more provided thata degree of stretch so high as to damage the filaments is avoided.Indeed, where the yarn is of a wholly synthetic material of a kind whosetensile strength and other textile properties can be developed orenhanced by hotor cold-drawing, the hotor cold-drawing operation can beemployed as the stretching operation immediately precedingfalse-twisting and setting. For this purpose the yarn may be given adegree of drawing of the order of 3 to 5 or even more times, accordingto the nature of the material. The stretching of the yarn, whether byway of hotor cold-drawing or to a more moderate degree may befacilitated, and the liability to filament damage reduced, by theapplication of heat or other softening agent to the yarn, though this isnot generally necessary if the degree of stretch does not exceed 7 /2%.The degree of softening thereby effected, however, should not be such asto relax the yarn entirely so that the stretch takes place under verylow or negligible strain whereby no substantial degree of stretch isrecoverable in the falsetwisting and setting zone.

The actual control of the degree of tension existing in thefalse-twisting and setting zone can be best con:

trolled, in practice, by positively controlling the linear speed ofwithdrawal of the yarn from said zone, and collecting the yarn sowithdrawn at a linear speed lower than that at which it is so withdrawn.Thus, withdrawal can be effected by means of draw-rollers or nip rollersrunning at a speed controlled (e.g. by means of an infinitely variablegear) in relation to that of stretching rollers by which the yarn is fedinto the zone, the rollers forwarding the yarn to a take-up devicedriven at a lower collecting speed. The speed of withdrawal shouldpreferably not exceed that at which the yarn is fed into the zone sincethis would impose a tension beyond that made available by the delayedrecovery of the yarn after stretching. Where a moderate degree ofcontraction or relaxation is to be allowed between the stretchingrollers and the take-up, e.g. of the order of 3 to 4%, the take-updevice may itself be used to determine the rate of withdrawal, withoutthe interposition of drawor nip-rollers for this purpose.

The false-twisting of the yarn can be effected by passing the yarn,before or after it passes through the setting zone, through afalse-twisting spindle, conveniently of the type in which the yarnpasses through a hollow and rapidly rotating spindle provided with meansfor guiding the yarn through several sharp changes of direction.Alternatively or in addition, however, by treating two or more yarnsassociated together and separating them from one another after theyleave the setting zone, the false-twist to which the yarns are subjectedmay be imposed wholly or in part by reason of a number of turns ofdoubling twist as between the yarns trapped in the path of the yarnsbefore the point of separation. In this case, it may be necessary tolimit the speed at which the materials are treated to avoid filamentdamage at the point of separation. The maximum speed will depend on thedenier of the yarn and may range, for example, from 4 metres per minutefor a total yarn denier of 30, up to 10 metres per minute for a denierof 150.

Setting of the twist can be effected by any convenient means, e.g. bypassing the yarn through a chamber containing wet steam at a temperatureappropriate to the nature of the yarn, or by passing it through achamber heated electrically or otherwise, or by passing it in contactwith a heated surface. The setting agency will generally have the effectof moderating the degree of tension to which the yarn is subjected bythe stretchrecovery of the yarn.

The invention is applicable to yarns generally, including staple fibreyarns, but is particularly applicable to continuous filament yarns, e.g.of reconstituted cellulose as in viscose yarns, of cellulose acetate orother organic derivative of cellulose and of wholly synthetic materialssuch as polyhexamethylene adipamide, polyaminocaproic acid,polyaminotriazoles, and polyethylene terephthalate.

By way of example some methods of carrying out the invention will now bedescribed in greater detail with reference to the accompanying drawingsin which:

Figure l is a diagrammatic side elevation showing the layout of one formof apparatus suitable for carrying out the invention;

Figures 2 and 3 show modifications of the layout of Figure 1; and

Figure 4 shows a similar side elevation of another form of apparatus forcarrying out the invention.

In Figure 1, a continuous filament yarn 5 is drawn over-end from asupply package 6, through a guide 7,

and thence to a pair of rollers 8, 9 round which it passes several timesand from which it is forwarded to a second and similar pair of rollers11, 12. The'roller I slightly skewed with reference to the rollers 8, 11and serve to lift the yarn from the surface of the rollers 8, 11 at eachturn, enabling the several turns to accommodate themselves along thelength of the rollers.

From the roller 11 the yarn proceeds upwards and diametrically through asteam header 13 of 2" diameter having a vertical offset tube 14 2 /2"long extending from its upper side. The offset tube 14' is provided witha yarn exit nipple 15 of smaller diameter, while the steam header 13 isprovided with an entry nipple 16 directly beneath the offset tube. adistance of about 3 therefrom, the yarn passes through false-twistingspindle 17 driven at about 15,000 r.p.rn., and thence upwards through aguide 18 vertical above the spindle 17. The yarn then passeshorizontally through a pair of nip rollers 19 which are rotated with asurface speed equal to or slightly below that of the stretching roller11, and which supply the yarn to a traverse guide 21 of a winding deviceby which it is guided to and traversed along the length of a package 22,driven at a constant surface speed lower than that of the nip rollers 19by means of a package-driving roller 23.

In the modification shown in Figure 2, the yarn 5 V leaving the supplyroller 8 passes in contact with a heated surface 25 on its way to thestretching roller 11, and

round a snubbing pin 26, which maybe positively ro- Y tated with asurface speed less than that of the roller 8. By these means thestretching of the yarn is facilitated by the softening action of theheated surface 25, and a substantial degree of stretch of the order of 3to 5 times or more can be effected. If it is desired to use the heatedsurface to facilitate a lower degree of stretch, say to 20%, thesnubbing pin 26 may be omitted, or the yarn caused to pass out ofcontact with it.

In the modification of the apparatus of Figure 1 shown in Figure 3, thenip rollers are omitted and the yarn 5, after leaving the guide 18,passes directly to the take-up device by which it is collected at alinear speed lower than that of the stretching roller 11. This form ofapparatus is suitable for use where a relatively small 7 reduction inspeed as between the stretching roller 11 and the take-up package 22 isdesired, e.g. of the order of 3 to 4%. suitable for a somewhat higherdegree of relaxtion up to 10% or more, when the relaxation, or most ofit, takes place between the nip rollers 19' and the package 22, andundue slackening and snarling of the yarn between the spindle 17 and thepackage is avoided.

In the layout of apparatus shown in Figure 4, two yarns 28 are drawnfrom separate supply packages 29 by way of guides 30, and are passedtogether round the supply rollers 8, 9 and the stretching rollers 11,12. The yarns then pass one on each side of a waisted guide roller 31beyond which they are temporarily twistedtogether. They pass together upan electrically heated tube 32 and thence through the false-twistingspindle 17, guide 18 and nip. rollers 19. On leaving the nip rollers19-the yarns 28 pass one on each side of a second waistedguide roller 33and are separately taken up on surface-driven collecting packages 34driven by contact with driving rollers 35. At the beginning of theoperation, the two yarns are twisted together beyond the guide 31 butbefore being passed one on each side of the separating guide 33. Theelfect of the rotation of the false-twisting spindle is to concentratethis twist mainly below the false-twisting spindle, in the setting zoneof said tube 32. The lower degree of twist (if any) between the yarns asthe approach. the separating roller 33, is easily held back by thatroller without undue strain on the yarns as they are separated.

Above the offset tube and at The arrangement of Fig. 1, however, is more4 The following are given as examples of the way in which the inventionis carried out:

Example I 5 Continuous filament yarn of polyhexamethylene adipamideformed of 23 filaments each of 3 filament denier is drawn from thesupply package 6 of Figure 1 by the 1 roller 8. The roller 8 is drivenwith a surface speed of 5 metres per minute, and the roller 11 at 5.5metres per 10 minute. The nip rollers 19 are rotated with a surfacespeed which may be varied from 5.3 to 5.5 metres per minute, and thepackage 22 is driven with a constant surface speed of 4.6 to 5 metresper minute.

Example II A cellulose acetate yarn of 100 denier is treated as inExample I, the supply roller 8 being driven at 8 metres per minute, thestretching roller 11 at 8.5 metres per minute, the withdrawing rolls at8.3 to 8.5 metres per minute and the take-up package at 7.5 to 8 metresper minute.

Example Ill A continuous filament yarn of polyhexamethyle'ncadipamide'formed of 23 undrawn filaments each of 12.

filament denier is drawn, as in Figure 2, from the supply package 6 bythe supply roller 8, which is driven at a speed of 1.25 metres perminute. The yarn then passes "in contact with the heated surface 25 andround the snubbing pin 26, and is forwarded by the stretching roller 11at a speed of 5.5 metres per minute, after which it is treated as inExample I.

Example IV A cellulose acetate yarn of 100 denier, as in Example 35 II,is drawn from a supply package at 8 metres per minute and forwarded intothe false-twist zone at 8.5 metres per minute, but is passed from theguide 18 directly to the package 22, as in Figure 3, the package beingdriven at a surface speed of 8.2 metres per minute. This allows acontraction between the stretching roller 11 and the package 22' of theorder of 3%. a degree of relaxation which is insufficient to give riseto difficulties of snarling or excessive ballooning in the yarn as itleaves the spindle '17.

Example V Two 30 denier yarns of polyaminocaproic acid each consistingof 6 continuous filaments are drawn from the two supply packages 29 ofFigure 2, the supply roller 8 being driven at 5 metres per minute andthe stretching roller 11 at 5.5 metres per minute. The nip rollers 19are driven with a peripheral speed of 4 metres per minute and thecollecting packages 34 at a speed of 3.75 metres per minutes. At thebeginning of the false-twisting operation the two yarns are twistedtogether before being passed one on each side of the separating guide 33so that the algebraic sum of the doubling twist as between the yarns,locked between the two waisted rollers 31, 33, is 1,800 turns.

Having described my invention, what I desire to' secure by LettersPatent is:

l. A method of producing a voluminous yarn, said method comprisingdrawing a yarn from a source of supply at one linear speed, forwardingthe yarn at a higher linear speed to a zone in which false-twist isimparted to said yarn, so as to stretch said yarn immediately before itenters said zone, setting in the fibres of the yarn the distortionimposed by said false-twist, withdrawing the yarn from said zone andcollecting it at a linear speed less than that at which it was fed intosaid zone.

2. Method according to claim 1, comprising positively withdrawing theyarn from the zone at a speed not greater than that at which it was fedinto said zone, and collecting it at a linear speed lower than that atwhich it is so withdrawn.

3'. Method according to claim 1, comprising stretching the yarn, withoutsoftening it, by up to 7.5% of its yarn initially associated withoutdoubling twist, associatoriginal length. ing them with doubling twist inthe false-twisting zone, 4. Method according to claim 1, comprisingsoftening and passing them on different sides of a separating guide theyarn being stretched so as to facilitate stretching. after they leavesaid zone so as to trap said doubling 5. Method according to claim 4,wherein the yarn is 5 twist in Said Zone- Softened by the apphcatlon ofheat References Cited in the file of this patent 6. Method according toclaim 1, wherein the falsetwist is imparted to the yarn by passing it inengagement UNITED STATES PATENTS with a rapidly rotated false-twistingspindle. 2,43 2,355 Truitt Dec. 9, 1947 7. Method according to claim 1,wherein false-twist 10 2,761,272 Vandamme Sept. 4, 1956 is imparted tothe yarn by using a plurality of ends of 2,810,281 Appleton Oct. 22,1957 Notice of Adverse Decision in Interference No. 91,290 involvingPatent No. 2,890,568, R. A. A. ON OF VOLUMINOUS YARN, final judgment ad-In Interference lered June 17, 1963, as to claim 1.

.Villens, PRODUCT I verse to the patentee was renc [Oflicial Gazette JMy 20, 1965.]

